The present invention relates to marking devices and, more particularly, to a marking stake which is especially useful for insertion in the surface of the ground to mark the location of an underground utility line or the like.
It is often necessary to determine and mark the location of underground utilities, such as gas lines, telephone lines, electric power lines, water mains and the like, so that they will not be damaged or ruptured by subsequent excavation activity. Once the location of a utility line is determined, markers of various types are inserted in the ground at spaced intervals immediately above and along the course of the underground utility. The most commonly used markers are stakes or other long, thin devices which are inserted into the ground and extend some distance above. The upper ends of the markers may typically include a small flag or other type of visual indicia to assist in locating the marker.
Wooden stakes have been used to mark the line of underground utilities but, because of their inherent large and bulky construction, the number of stakes that a user can conveniently handle is severely restricted and marking long distances is tedious and time consuming. Wooden stakes also typically require some type of device to drive them into the ground and their inherent bulk also presents storage and transportation problems.
Long pieces of relatively narrow gauge wire have also been used for markers. Typically, a 24" length of wire with a small plastic flag attached to the upper end is inserted into the ground. The use of wire shaft markers has, however, been restricted because of the problems of safety and the need to often preliminarily form a hole in the ground by another means because the thin wire shaft will not withstand insertion without bending.
Another type of marker, intended to overcome the problems previously described comprises a long hollow plastic tube, similar to a drinking straw, with a small plastic flag attached to one end. Such markers essentially eliminate the safety hazards associated with markers having wire shafts, but these thin hollow plastic markers normally require the pre-forming of a hole in the ground to prevent bending or collapse of the thin body upon insertion. Also, the thin hollow shaft on this type of marker has a tendency to fold relatively easily at the ground line after insertion.
Markers with thin solid plastic or fiberglass shafts have been substituted for those made with wire or hollow plastic. These markers are generally considered to be somewhat safer than those using wire shafts, but their semi-rigid shafts still present a potential hazard. Pre-forming holes for their receipt is also very often required.
U.S. Pat. No. 3,267,901 (Carroll) describes a wooden marking stake to the top of which a cluster of strands are attached, as with a staple, to provide a "flag" to help facilitate its location.
U.S. Pat. No. 3,523,515 (Brown) describes a marking device for more or less permanently establishing the location of an underground utility line. A series of strap-like stakes are attached at spaced intervals directly to the line after it is laid and before backfilling. The marking devices are long enough to extend above the final grade after backfilling.
U.S. Pat. No. 3,758,062 (Caldwell et al) shows a disposable, multi-purpose stake which, in one embodiment, includes a small banner or flag attached to the top thereof to facilitate its location when used as a marking stake.
U.S. Pat. No. 4,649,678 (Lamson) discloses a marking stake combination including a hollow cylindrical receptacle adapted to be driven into the ground and into which a marking stake or post may be removably inserted.
All of the stakes described in the foregoing patents are much too bulky, expensive, difficult to use, or otherwise unsuitable for use in utility line location marking where large numbers of stakes are typically required. There thus remains a need for a location marking device which is inexpensive, small in size, easy to insert into the ground, safe and reliable.